U.S. patent number 4,986,601 [Application Number 07/437,101] was granted by the patent office on 1991-01-22 for tilting mechanism for supporting seat portion and backrest of chair in integral fashion.
This patent grant is currently assigned to Itoki Co., Ltd.. Invention is credited to Noboru Inoue.
United States Patent |
4,986,601 |
Inoue |
January 22, 1991 |
Tilting mechanism for supporting seat portion and backrest of chair
in integral fashion
Abstract
A tilting mechamism for supporting a seat portion and a backrest
of chair in integral fashion. This mechanism comprising an upright
support; a pedestal block mounted on an upper end of the upright
support for swivel movement; an arm member pivotally engaged at the
rear side thereof by a first horizontal shaft mounted on the
pedestal block toward the front of the upright support; a seat
plate pivotally engaged at a front portion thereof with the end of
this arm member by a second horizontal shaft; an elastic body such
as a spring lying between this plate and the block; a backrest
supporting member on which a backrest can be mounted, the
supporting member being elongated and carried in part on the lower
face of the seat plate and pivotally engaged with a long hole
formed at the rear end of the seat plate by a third horizontal
shaft; the forward part of this supporting member mounted on the
pedestal block by the first shaft pivotally engaging the arm member
with the block; and a gas spring connecting between a fourth shaft
mounted on the front end of this supporting member and the second
shaft positioned at the front end of the arm member.
Inventors: |
Inoue; Noboru (Tokyo,
JP) |
Assignee: |
Itoki Co., Ltd. (Osaka,
JP)
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Family
ID: |
15593589 |
Appl.
No.: |
07/437,101 |
Filed: |
November 16, 1989 |
Foreign Application Priority Data
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Nov 30, 1988 [JP] |
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63-154864[U] |
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Current U.S.
Class: |
297/300.4;
297/320; 297/300.5 |
Current CPC
Class: |
A47C
1/03272 (20130101); A47C 1/03261 (20130101); A47C
1/03283 (20130101); A47C 1/03255 (20130101) |
Current International
Class: |
A47C
1/032 (20060101); A47C 1/031 (20060101); A47C
001/032 () |
Field of
Search: |
;297/300-302,316,320 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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240389 |
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Oct 1987 |
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EP |
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3605809 |
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Aug 1987 |
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DE |
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Primary Examiner: Brown; Peter R.
Attorney, Agent or Firm: Rogers & Killeen
Claims
What is claimed is:
1. A tilting mechanism for supporting a seat portion that extends
forwardly and a backrest of a chair in integral fashion,
comprising:
an upright support;
a pedestal block for swivel movement mounted on the upper end of
said upright support;
an arm member having a rear end pivotally engaged with said
pedestal block by a first horizontal shaft carried forwardly of
said upright support;
a seat plate having a front portion pivotally engaged with a front
end of said arm member by a second horizontal shaft;
an elastic body lying between said seat plate and said pedestal
block;
a backrest supporting member on which a backrest can be mounted,
carried in part below said seat plate, said backrest supporting
member being pivotally engaged at a rearwardly extending portion
with a rear portion of said seat plate by a third horizontal shaft
carried in an oblong hole in said seat plate and pivotably engaged
at a forwardly extending portion with said pedestal block by said
first horizontal shaft; and
a gas spring 7 connecting between a fourth shaft mounted on a front
end of said backrest supporting member and said second horizontal
shaft.
2. A tilting mechanism for supporting a forwardly extending seat
and upwardly extending backrest of a chair having an upright
support, comprising:
a pedestal block rotatably carried by the upper portion of said
upright support;
an arm member having a rear end pivotably engaged with said
pedestal block by a first shaft carried forwardly of said upright
support;
a seat plate for carrying the seat, having a front portion
pivotally engaged with a front end of said arm member by a second
shaft;
a backrest supporting member for carrying the backrest, having
a rearwardly extending portion pivotably engaged with a rear
portion of said seat plate by a third shaft carried in an oblong
hole in said seat plate and
a forwardly extending portion pivotably engaged with said first
shaft; and
spring means pivotably engaged with said second shaft and with said
backrest supporting member by a fourth shaft positioned forwardly
of said first shaft.
3. The mechanism as defined in claim 2 wherein said backrest
supporting member bifurates rearwardly of said upright support and
has two members extending forwardly thereof.
4. The mechanism as defined in claim 2 wherein said oblong hole has
a major axis extending generally horizontally.
5. The mechanism as defined in claim 2 wherein said arm member is
U-shaped, with said pedestal block positioned therein and with two
arms extending forwardly of said pedestal block.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to tilting mechanisms
suitable for use with chairs such as office chairs and, more
particularly, to tilting mechanisms for the seat portions of such
chairs as well as an interlocking tilting mechanism for supporting
the seat portions to allow integral movement with the backrest.
2. Description of the Related Art
Recently, in the chairs used in the office many mechanisms which
interlockingly tilt a seat portion with its backrest have been
proposed and some of them are now in use.
However, most of the conventionally proposed interlocking
mechanisms that tilt the seat portion together with the backrest,
are arranged so that when the seat portion is sunk by the weight of
the person using the chair the backrest leans backward and
interlocks, or so that when a person leans into the backrest the
seat portion sinks interlockingly at the same time that the
backrest leans backward.
However, the posture with which a person sits on an office chair is
not limited to a posture which can be coped with by the
conventional interlocking mechanisms. For example, a person may sit
on the chair while distributing his weight so that the front side
of the seat portion sinks to its forward side.
In this case, there are problems in (1) that the chairs do not cope
with the posture with the conventional interlocking mechanisms, (2)
the forming cost of the constituent members is high, (3) there is a
troublesome fabrication, or (4) a rough action is induced because
of their complex structure even if an interlocking mechanism is
installed.
In addition, the feeling of sitting on the chair becomes unpleasant
because the abdominal region of the person sitting is compressed
when he sits on the chair with a slouching posture if the seat
portion is not sunk and forward.
SUMMARY OF THE INVENTION
A tilting mechanism for supporting a seat portion and a backrest of
a chair in integral fashion. This mechanism comprising an upright
support; a pedestal block mounted on an upper end of the upright
support for swivel movement; an arm member pivotally engaged at the
rear side thereof by a horizontal shaft mounted on the pedestal
block toward the front of the upright support; a seat plate
pivotally engaged at a front portion thereof with the end of this
arm member by a second horizontal shaft; an elastic body such as a
spring lying between this plate and the block; a backrest
supporting member on which a backrest can be mounted, the
supporting member being elongated and carried in part on the lower
face of the seat plate and pivotally engaged with a long hole
formed at the rear end of the seat plate by a third horizontal
shaft; the forward part of this supporting member mounted on the
pedestal block by the first shaft pivotally engaging the arm member
with the block; and a gas spring connecting between a fourth shaft
mounted on the front end of this supporting member and the second
shaft positioned at the front end of the arm member.
It is therefore an object of the present invention to provide a
tilting mechanism without the aforementioned problems. According to
the present invention, this object is accomplished by providing a
tilting mechanism for supporting the seat portion and backrest of a
chair in integral fashion, comprising an upright support; a
pedestal block mounted on an upper end of the upright support for
swivel movement; an arm member pivotally engaged at the rear side
thereof by a first horizontal shaft mounted on the pedestal block
toward the front of the upright support; a seat plate pivotally
engaged at one of its ends with the end of the arm member by a
second horizontal shaft; an elastic body, such as a spring, lying
between the seat plate and the block; a backrest supporting member
on which a backrest can be mounted, the supporting member being
elongated and carried on the lower face of the seat plate and
pivotally engaged with a long hole formed at the rear end of the
seat plate by a third horizontal shaft; the forward part of the
backrest supporting member being mounted on the pedestal block by
the first shaft pivotally engaging the arm member with the block;
and a gas spring connecting between a fourth shaft mounted on the
front end of the backrest supporting member and the second shaft
positioned at the front end of the arm member.
The seat plate can tilt vertically both forward and backward of the
first shaft because it is installed by the second shaft at the
front end of the arm member and tiltably engaged with the pedestal
block by the first shaft.
The seat plate and the backrest supporting member each tilt
interlockingly with the tilting of the other since the backrest
supporting member pivotally engaged with the pedestal block by the
first shaft for common use is connected with the seat plate at the
front and rear parts of the seat plate through the long hole,
second, third and fourth shafts and the gas spring.
These and other objects, features and advantages of the present
invention will become apparent from the following detailed
description of a preferred embodiment thereof taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic side elevation in cross section of a
preferred embodiment of a mechanism of the present invention in the
state in which no weight is loaded;
FIG. 2 is a diagrammatic side elevation in cross section of a
preferred embodiment of a mechanism of the present invention in the
state in which a seat plate is most sunken and the backrest
supporting member is tilted farthest backward; and
FIG. 3 is a diagrammatic perspective view of the whole mechanism of
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings, an upright support in the same pole shape as that
for a common swivel chair typically used in an office is indicated
as 1, and the gas spring (which does not appear in the figure)
incorporated in the upright support makes it possible to change its
height within a specified range. A valve rod la opening and
shutting the valve of this gas spring and an operating lever 1b
pushing down this valve rod 1a are shown as the cross sections.
A pedestal block 2, in block shape mounted on the upper end of said
upright support 1, forms a pedestal 2b in plate-like shape in front
of the body 2a and a horizontal bearing 2c in a direction parallel
to that of the width of a pedestal plate 4 in front of the central
axis of the upright support 1.
An arm member 3 formed in U (or hairpin) shape in a horizontal
plane. While this arm member 3 is pivotally mounted on said block 2
by a shaft A, it is positioned so that the bent-up rear end side
covers the block 2, and its open ends are pivotally engaged with
the front end of a seat plate 4 (which is described later) by a
shaft B.
The seat plate 4 is a plain plate on which a seat sheet SE is
mounted and side walls 4a are formed on both sides when viewed from
the front. The front end of the side walls 4a are pivotally engaged
with the front end of said arm member 3 with a shaft B, and a long
hole C is formed at the rear end of the side walls 4a. This long
hole is pivotally engaged with a supporting member 6 of a backrest
BA, which is described later, with a shaft D.
An upper pedestal 4b is formed at the part corresponding to the
lower pedestal 2b of the pedestal block 2 on the lower face of
aforementioned seat plate 4. A coil spring 5 is installed between
both upper pedestals 4b and lower pedestal 2b in the example of
this figure. Another type of spring or elastic body such as a
rubber band and so on may be installed instead of this spring
5.
A supporting member 6 is shown on which a backrest BA is mounted.
Its lower side is bent and elongated so that it can be positioned
on the lower face of the seat plate 4 and the end side of an
elongated part 61 of this supporting member 6 is formed as
sheared-leg shape so that the pedestal block 2 or the arm member 3
can be put between the elongated part 61.
The connecting projecting parts 6a, 6a and 6c are formed on the
upper face of the elongated part 61 of this member 6 in order to
connect with another member in this embodiment of the figure.
While said supporting member 6 is pivotally engaged with the
connecting projecting part 6b by the shaft A of the pedestal block
2, the connecting projecting part 6c positioned at the rear end of
said supporting member 6 is connected with a long hole C of the
seat plate 4 by a shaft D. Supporting member 6 is
interconnectically installed on the pedestal block 2 and the seat
plate 4 by connecting a gas spring 7 between a shaft E mounted on
the projecting part 6a of the front end and the shaft B connecting
the seat plate 4 with the arm member 3.
The gas spring 7 can adjust the rate of projection of a rod 7b
which peeps out from the cylinder by controlling the opening and
shutting of a regulating valve 7a. It can be also controlled by
installing a coil spring in which a resiliency controlling
mechanism is added in the shafts E and B instead of this gas
spring.
The mechanism of this invention thus constructed works as
follows.
When a person sits on the seat sheet SE, the weight of the person
is applied as a load to the seat plate 4 containing the seat sheet
SE and supported by pedestal 2b of the pedestal block 2 through the
spring 5.
While the weight near the center point of the seat plate is
supported by the pedestal 2b through the spring 5 in this
condition, the front end of this plate 4 is connected with the
front end of the arm member 3, which is supported by the block 2 at
the front end thereof through the shaft A, and the rear end of the
seat plate 4 is connected with the connecting projecting part 6c of
the backrest supporting member 6, which is supported by the
pedestal block 2 by the shaft A. Therefore, the seat plate 4 can be
rocked in the sinking direction of the seat plate 4 at the forward
and backward edges of the plate 4 round a shaft A.
Since the front end of this plate 4 is connected with the
connecting projecting part 6a formed at the front end of the
backrest supporting member 6 through the gas spring 7 and the rear
end of the seat plate 4 is connected with the connecting projecting
part 6c of the backrest supporting member 6 through the long hole C
and the shaft D, this sinking at the forward and backward edges of
the plate 4 is accompanied by the forward and backward inclining
movement of the supporting member 6 on which the backrest BA is
mounted.
When the seat plate sinks at the front end side, this sinking
action induces the rise of the rear part of the plate 4 round the
shaft A co-operating with the arm member 3 at the same time that
the sinking action pushes the connecting projecting part 6a of the
end of the backrest supporting member 6 backward through the gas
spring 7. When this supporting member 6 is pushed from the front
side, this sinking action is converted into a counter-clockwise
angular rotation because this supporting member is pivotally
engaged with the shaft A. This counter-clockwise angular rotation
synchronizes with the rise of the rear part of the plate 4 at the
long hole C and the shaft D which connects them.
On the other hand, when the seat plate 4 sinks at the rear end side
thereof, this sinking action works round the shaft B of the arm
member 3 and induces the synchronized backward leaning action of
this supporting member 6.
At this time the plate 4 leans backward round the shaft B because
the rear end wall 3a of the arm member 3 strikes the rear face of
the body 2a of the pedestal block 2 and inhibits the
counter-clockwise angular rotation of the arm member 3 round the
shaft A.
The above mentioned synchronous action is also induced by the
sinking of the rear side of the seat plate 4 when the backrest
supporting member is leant backward.
For the constituent mechanical members of this invention which are
shown in the aforementioned description, ready-made articles are
used as the coil spring 5 and the gas spring 7. In addition, since
the shapes of the upright support 1, pedestal block 2, arm member
3, seat plate 4, backrest supporting member 6 and so on, are
simple, these member can be manufactured easily by casting and
forging of metals, press working of sheet metal and so on, or by
the forming of synthetic resin.
As described above, there are advantages in tilting of the seat
plate corresponding to the posture of the person who sits on it and
in interlocking by tilting the backrest, and the tilting of the
seat plate corresponding and interlocking to the tilting of the
backrest can be accomplished smoothly because the seat plate is
formed to be able to tilt both forward and backward and the
supporting member on which the backrest is mounted is connected
with this seat plate so that the supporting member acts
interlockingly with that of the seat plate. A further advantage
relates to manufacturing the mechanism in that the components have
a simple structure and the number of members is relatively
small.
Therefore, the present invention offers significant utility as a
tilting mechanism interlockingly sinking of the seat plate with the
tilting of the backrest for use with office chair.
* * * * *